year = int(input("请输入一个年份："))
if year % 4 == 0:
    if year % 100 == 0:
        if year % 400 == 0:
            print(year, "年是闰年")
        else:
            print(year, "年不是闰年")
    else:
        print(year, "年是闰年")
else:
    print(year, "年不是闰年")